Oji Holdings Corporation

Yuichi Shishido

Tadakazu Ishiwata

Yoshinori Matsuo

Masahiro Nakata

Kazuo Ikeda

Akihiro Kakehi

Shigeo Murase

Provided is a biaxially stretched polypropylene film for capacitors having a thin thickness and having excellent initial voltage resistance and excellent long-term heat resistance and voltage resistance, and also provided is a metallized polypropylene film for capacitors. The polypropylene film for capacitors is obtained by biaxially stretching a polypropylene resin, the polypropylene film having a crystallite size of 122 &#x212b; or less as determined by the Scherrer's equation from the half width of the reflection peak from (040) plane of &#x3b1;-crystal measured by a wide angle X-ray diffraction method, and the polypropylene film having a value of birefringence &#x394;Nyz with respect to a thickness direction of 7.0&#xd7;10or more and 10.0&#xd7;10or less as measured by an optical birefringence measurement.

Biaxially stretched polypropylene film for capacitor

A biaxially stretched polypropylene film for a capacitor containing an isotactic polypropylene. The weight average molecular weight (Mw) of the isotactic polypropylene as measured by gel permeation chromatography (GPC) is 250,000 to 450,000, the molecular weight distribution Mw/Mn is 7 to 12 and Mz/Mn is 20 to 40, and the value of a difference obtained by subtracting a differential distribution value when the logarithmic molecular weight Log(M)=6 from a differential distribution value when Log(M)=4.5 on a molecular weight distribution curve thereof is 8% to 20%. The ultrathin biaxially stretched polypropylene film for a capacitor has superior heat resistance performance and withstands voltage performance.

Biaxially stretched polypropylene film for capacitors

A biaxially-oriented polypropylene film for an ultra-thin capacitor that has superior heat resistance, withstand voltage performance and long-term durability. The film has a stereoregularity in which mesopentad fraction (mmmm) as determined by measurement of high temperature nuclear magnetic resonance (high temperature NMR) is between 94% and 98%, a weight average molecular weight (Mw) of 250,000 to 450,000, a molecular weight distribution (Mw/Mn) of 4 to 7, and on a molecular weight distribution curve, a difference determined by subtracting the differential distribution value when the logarithm of molecular weight Log(M)=6 from the differential distribution value when Log(M)=4.5 that is 9% to 15%. The film is fabricated using a polypropylene raw material resin in which the composition of the aforementioned molecular weight distribution has been adjusted by peroxidative decomposition treatment of a polypropylene resin.

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Otsu, Japan

Yuichi Shishido